Recently, it has become more common to take samples of inner tissue of man and animals, so-called biopsy, in order to diagnose various diseases such as cancer. The reasons for this development include, on the one hand, that it is a reliable diagnosing method and, on the other hand, that sampling devices have been developed which are easy to use even for physicians who are not specialized in this sampling field.
A prior-art sampling device of this type is described in the Swedish patent application No. 8600755-6, which corresponds to U.S. patent application Ser. No. 890,543, now U.S. Pat. No. 4,699,154, where also the sampling procedure proper is described. The driving unit therein described is intended to be used to drive a needle unit and comprises a pair of springs which together with various guiding, locking, and triggering mechanisms are enclosed in a little box which also forms the handle of the sampling device. All the details in the box proper are made of corosion-free material of high quality, for example stainless steel. This box with its contents is impractical for the reason that it is complicated and heavy, the latter factor causing the physician to become tired when carrying the instrument. Due to the fact that the device is complicated and contains comparatively expensive material, the whole construction becomes expensive. This driving unit, however, may be sterilized and reused practically indefinitely.
However, there has been a demand for a sampling device of the above-indicated type that would be so inexpensive and simple as to be considered a single-use device, even if it is capable of being used multiple times prior to being discarded. Such a device, even though primarily intended for only a single use, could be used more than once when several samples are to be retrieved from the same patient. Moreover, there is a need for a sampling device which is lightweight so as not to fatigue the user, which has an ergonomically comfortable shape, and which permits easy tensioning of the springs of the driving unit.